Too much of a good thing?

SACRAMENTO, Calif., July 13, 2020-The governor's office today issued an emergency executive order restricting the home charging of plug-in electric vehicles (PEV) to every other day. The recent extreme heat across the state has triggered an expected uptick in electricity demand for air conditioning. What was not expected was the rapid growth of PEV use over the past five years that has raised the base level of residential electricity demand beyond forecasted levels. The narrower margin between California's annual electricity production capacity and consumption levels has triggered more frequent rolling brownouts and blackouts.…

That news story is imaginary. Whether such a worst-case scenario materializes depends on the popularity of PEVs such as the Chevrolet Volt. Motor Trend magazine's Car of the Year for 2011 has all the makings for a popular breakthrough technology. It can be driven up to 40 miles on a single eight-hour charge (four hours with the special 220-volt kit) but has a small gasoline engine that can recharge the battery and extend the range. The typical commuter drives fewer than 40 miles per day, so a PEV owner might never have to use gas at all.

In all-electric mode, a PEV is over three times more efficient than a traditional gasoline-powered vehicle, and with electricity prices competitive with gasoline, consumers should benefit from lower energy costs.

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But if retail prices of PEVs drop to a level where they become competitive with traditionally powered vehicles (the MSRP for the Volt is around $40,000), the resulting increase in the percentage of PEVs will shift a significant amount of transportation energy use from a decentralized gasoline-oriented fueling infrastructure to the centralized electrical power grid.

A 2009 study by the California Energy Commission projects statewide electricity consumption from dedicated electric vehicles and plug?in hybrids to be around 4,400 gigawatt hours by 2020, only 4 percent of total residential consumption. Yet this figure is based on two important assumptions: that only half the annual driving mileage for PEVs will be all-electric and the market penetration of PEVs will be relatively low.

A PEV market penetration study commissioned by the Swiss government estimates that by 2020, 15 percent of that country's national car fleet will be electric vehicles. Another study by the University of California, Berkeley, forecasts that by 2030, 24 percent of U.S. cars on the road will be PEVs. Using this 15 percent figure and the current number of registered automobiles in California, the estimated electricity consumption in 2020 should be closer to 10 percent.

Assuming most PEV drivers operate their vehicles mostly in all-electric mode, this percentage rises to 18 percent and pushes the total projected electricity consumption above projected capacity for 2020.

The future of personal transportation appears to be electric, and this major shift will likely begin with innovative states like California, where policymakers must also tackle the tough problems of adding more power generation capacity to meet the demand.

Michael Cochrane

Michael is a retired Defense Department engineer and former Army officer who is an adjunct professor of engineering management at Old Dominion University in Norfolk, Va. He is a graduate of the World Journalism Institute's mid-career course. Follow Michael on Twitter @MFCochrane.